import java.util.Scanner;

/**
 * Created by dllo on 18/3/30.
 */
public class Question01 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.println("输入一个数字");
        int a = scanner.nextInt();
        int b = 0;
        int c = 0;

        for ( b = 0; b <= a; b++) {
             c = c + b;
        }
        System.out.println("和:" + c);

    }
}
